Although beer has a lower freezing point than water, it will freeze if left in a freezer for too long. The exact length of time varies depending on the beer. A frozen beer can sometimes be saved, but it usually isn't something you'd want to drink as it's often flat. However, all is not lost. Just thaw it and use the beer in a sauce, marinade, stir-fry or include it as part of a soup base.
Freezing Point
Beer consists of alcohol and other substances dissolved in water, giving it a lower freezing point than water. The actual freezing point varies depending on the beer's content. Initially, some of the water freezes out of the solution. This is "fractional freezing" and is used in creating eisbock, a high-alcohol beer. However, be aware that as the water freezes, it expands; this can force the cap off a bottle. In some instances the bottle may break. Freezing also causes canned beer to bulge. It's best to avoid putting bottles into the freezer unless you know you won't forget to remove them after they've chilled.
Chilling Beer Quickly
To chill beer quickly without a freezer, immerse cans or bottles in a mixture of ice and water. The more ice there is in the mixture, the better this process will work. Sprinkle several tablespoons of coarse salt over the top of the mixture. The salt lowers the melting point of the ice. As the ice melts, it draws heat from the surrounding water and the beer, chilling it in only a few minutes.
Ideal Serving Temperature
Quite apart from the potential freezing hazard, few beer experts recommend putting a beer in the freezer. Low temperatures suppress the flavors and aromas of the beer. The ideal beer serving temperature varies depending on the beer, but for most beers, it's at or just below cellar temperature -- 46 to 55 degrees Fahrenheit.